Sootblower having a rotational delay mechanism

ABSTRACT

A sootblower to project a blowing medium into a boiler is disclosed herein. The sootblower includes a hub, in which a first end of the hub is configured to receive a lance and a second end of the hub is configured to receive the blowing medium. The sootblower further includes a drive assembly configured to convert bidirectional rotation from a drive shaft to bidirectional rotation for the hub. The drive assembly then includes a rotation delay mechanism configured to delay a transition between a first directional rotation and a second directional rotation of the bidirectional rotation for the hub with respect to the drive shaft when the drive shaft is transitioning from a first directional rotation to a second directional rotation of the bidirectional rotation for the hub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit, under 35 U.S.C. § 119, of U.S.Provisional Application Ser. No. 60/911,245, filed on Apr. 11, 2007 andentitled “Sootblower Having a Rotational Delay Mechanism” in the name ofW. Wayne Holden and Michael C. Holden. The disclosure of this U.S.Provisional Application is incorporated herein by reference in itsentirety.

BACKGROUND OF DISCLOSURE Field of the Disclosure

Embodiments disclosed herein generally relate to sootblowers. Morespecifically, embodiments disclosed herein relate to an improvedsootblower used to project a stream of a sootblower medium within acombustion device.

Generally when combusting fuel in large boilers, as used in electric andsteam generating plants, or in recovery boilers, as used in paper andpulp mills, large quantities of particulate matter from burned fuel mayquickly accumulate within the interior surfaces and tubes of theboilers. Specifically, the particulate matter, such as soot and tar, mayaccumulate on the heat exchanger surfaces and tubes in these boilers tosignificantly reduce the boilers' efficiencies. To prevent suchparticulate matter buildup, sootblowers may be used to provide asubstantially continuous cleaning of the interior surfaces of theboilers.

Typically, sootblowers are permanently installed between adjacent rowsof heat exchanger tubes within a boiler so that the sootblowers mayprovide regular, if not substantially continuous, cleaning without theneed for the boiler to be taken out of service during the cleaning. Assuch, it is common for each of the large boilers and the paper millboilers to have up to fifty or more sootblowers attached for cleaning.To maintain operating efficiency, each sootblower may be operated on aregular cycle, such as about once an hour, depending on the size of theboiler and severity of the accumulation of particulate matter.

One commonly used sootblower are long retracting sootblowers. Examplesof long retracting sootblowers are shown and described in U.S. Pat. Nos.5,675,863 and 5,745,950, which are incorporated by reference in theirentirety. These sootblowers generally include a long pipe or lancehaving a nozzle at the end for directing a blowing medium, such as steamor another vapor, onto the surfaces of the heat exchanger tubes. Anexample of a lance 102 cleaning a boiler 190 is shown in FIG. 1. Lance102, having nozzles 104 at an end for directing a blowing medium 106, isinserted through a hole 194 of a wall 192 of boiler 190. Lance 102usually is sufficient in length such that the entire length of heatexchanger tubes 196 of boiler 190 may be accessed by lance 102. Lance102 is then usually attached to a moveable carriage or housing with amotor (not shown) to reciprocate and rotate (as indicated by arrows)lance 102 within boiler 190 for effective cleaning. As such, uponactuation, lance 102 may reciprocate into boiler 190 and rotate at agenerally continuous speed. Blowing medium 106 is then exerted throughnozzles 104 as lance 102 is in motion, thereby blowing off accumulatedparticle matter 198 and cleaning heat exchanger tubes 196.

When actuated and reciprocated into and out-of the boiler, the lancegenerally will follow a standard helical path, as shown in FIG. 2.Specifically, the nozzle of the lance may follow path 280 when extendedinto and retracted from the boiler. However, as the nozzle follows path280, substantial portions of the boiler and the heat exchanger tubes mayfail to be reached by blowing medium from the nozzle of the lance. Thus,particulate matter may still accumulate on the boiler's internalsurfaces and heat exchanger tubes that do not fall within path 280 ofthe nozzle of the lance. Accordingly, there exists a need for asootblower that may improve the coverage of the nozzle of the lance toprovide more coverage when cleaning boilers, thereby increasing theefficiency of the boilers.

SUMMARY OF CLAIMED SUBJECT MATTER

In one aspect, embodiments disclosed herein relate to a sootblower toproject a blowing medium into a boiler. The sootblower includes a hub,in which a first end of the hub is configured to receive a lance and asecond end of the hub is configured to receive the blowing medium. Thesootblower further includes a drive assembly configured to convertbidirectional rotation from a drive shaft to bidirectional rotation forthe hub. The drive assembly then includes a rotation delay mechanismconfigured to delay a transition between a first directional rotationand a second directional rotation of the bidirectional rotation for thehub with respect to the drive shaft when the drive shaft istransitioning from a first directional rotation to a second directionalrotation of the bidirectional rotation for the hub.

In another aspect, embodiments disclosed herein relate to a driveassembly for a sootblower to project a blowing medium into a boiler. Thedrive assembly includes a drive shaft, a static member attached to thedrive shaft, and a spur gear disposed about and configured to rotateabout the drive shaft. One of the static member and the spur gearincludes a pint attached thereto, and the other of the static member andthe spur gear includes a slot formed therein. The pin then slidablyengages the slot.

In yet another aspect, embodiments disclosed herein relate to asootblower used to project a blowing medium. The sootblower includes ahousing having a lubricant disposed therein, roller rotatably attachedto the housing and configured to travel along tracks, and bearingdisposed inside of the rollers. The bearings of the rollers are in fluidcommunication with the housing.

Other aspects and advantages of the invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a view of a prior art lance attached to a sootblower.

FIG. 2 shows a view of helical path of a prior art sootblower.

FIG. 3 shows a top-down view of a sootblower in accordance withembodiments disclosed herein.

FIG. 4 shows a cross-sectional view taken along line A-A of thesootblower shown in FIG. 3 in accordance with embodiments disclosedherein.

FIG. 5 shows a perspective view of a spur gear in accordance withembodiments disclosed herein.

FIG. 6 shows a view of a helical path of a sootblower in accordance withembodiments disclosed herein.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to an improvedsootblower with a rotation delay mechanism. The rotation delay mechanismmay include one member with a pin to engage or another member with aslot. In another aspect, embodiments disclosed herein relate to a driveassembly having a static member attached to a drive shaft and a spurgear disposed about the drive shaft. A pin is attached to one of thestatic member and the spur gear, and a slot is formed in the other ofthe static member and the spur gear. In yet another aspect, embodimentsdisclosed herein relate to a sootblower configured to have bearings ofrollers in fluid communication with a housing of the sootblower, therebyallowing lubricant disposed within the housing to flow between thebearings and the rollers.

Referring to FIG. 3, a sootblower 300 in accordance with embodimentsdisclosed herein is shown. Sootblower 300 includes a housing 301configured to receive a lance 302. Lance 302 may have a long, tubularconstruction and include one or more nozzles 304. As shown, nozzle 304,preferably a venturi nozzle, is disposed at the end of lance 302.However, those having ordinary skill in the art will appreciate that theinvention is not so limited, and the nozzle may be disposed at anylocation on or about the lance. Nevertheless, lance 302 is configured toconnect with a hub 310, such as connecting a flange 308 of lance 302with a flange 312 of hub 310.

Hub 310 may be rotationally disposed within housing 301 such that hub310 is able to rotate with respect to housing 301. As such, when hub 310rotates, lance 302 will accordingly rotate therewith. Further, hub 310is configured to receive a blowing medium, such as through a feed tube317. As shown, a valve 316 may supply the blowing medium to feed tube317, in which the blowing medium may then be transported through hub 310to lance 302 to exert the blowing medium through nozzle 304. In oneembodiment, the blowing medium used may be steam, such as superheatedsteam of about 750° F. (400° C.); however, any high-pressure and/orhigh-temperature vapor or gas known in the art may be used.

Sootblower 300 further includes a motor 318 configured to supply powerand provide rotational movement to hub 310 and translational movement tohousing 301. Specifically, using a drive assembly disposed withinhousing 301, motor 318 rotates hub 310 and lance 302, in addition tomoving housing 301 along tracks 322. In one embodiment, rollers 320 maybe rotatably attached to housing 301. As shown in FIG. 3, rollers 320are rotatable attached to housing 301 through legs 324. Rollers 320 maythen travel along tracks 322 to support the weight and enabletranslational movement for sootblower 300. Thus, when used in a boilercleaning application, the lance of the sootblower may be reciprocatedinto and out-of the boiler while rotating. An example of motor 318 thatmay be used within sootblower 300 is a 1,750 revolutions per minute (183radians per second), 2 horsepower (1.5 kilowatts) electric motor. Thosehaving ordinary skill in the art though will appreciate that anysuitable motor may be used.

Referring now to FIG. 4, a view of a cross-section taken along line A-Aof sootblower 300 of FIG. 3 in accordance with embodiments disclosedherein is shown. Sootblower 300 includes a drive assembly 330 disposedwithin housing 301. Generally, drive assembly 330 is configured toreceive bidirectional rotation from the motor (e.g., 318 shown in FIG.3) of the sootblower. This bidirectional rotation is then converted bydrive assembly 330 into bidirectional rotation for hub 310. Thus, as thehousing of the sootblower travels back-and-forth along the tracks toextend and retract the lance within the boiler, the lance willaccordingly transition back-and-forth between rotational directions.

For example, when the sootblower is translationally moving along thetrack towards the boiler with the lance being extended into the boiler,the motor and the hub/lance may rotate in the clockwise direction. Then,when the sootblower is translationally moving along the track away fromthe boiler with the lance being retracted from the boiler, the motor andthe hub/lance may reverse directions to rotate in the counter-clockwisedirection. Thus, bidirectional rotation from the motor is convened intobidirectional rotation for the hub and the lance attached thereto.

Further, in addition to converting the rotation from the motor to thehub 310, drive assembly 330 may be used to delay the transition betweenthe rotational directions from the motor to hub 310. Such a delay mayinclude temporarily stopping the hub or discontinuing to providerotation to the hub when the motor switches directions. For example,when the motor transitions from rotating in a clockwise direction torotating in a counter-clockwise direction, the transition of rotation ofthe hub/lance may have a delay from the transition of rotation of themotor. This delay between the transition of the motor and the transitionof the hub/lance may thereby allow the nozzle of the lance to providemore coverage when cleaning the sootblowers, essentially allowing thenozzle to follow different helical paths when extending within andretracting from a boiler. This delay between the transition of the motorand the transition of the hub/lance is described further below.

Referring still to FIG. 4, motor 318 generally provides bidirectionalrotation to a drive shaft 340 of drive assembly 330. Specifically, themotor may provide bidirectional rotation to a worm 326. Worm 326,disposed within housing 301, is configured to bidirectionally rotate,corresponding to the bidirectional rotation of the motor. For example,as the motor rotates clockwise and then counter-clockwise, worm 326 maycorrespondingly rotate clockwise then counter-clockwise. Worm 326 isthen configured to engage a worm gear 342, attached to drive shaft 340.As such, the motor is configured to bidirectionally rotate drive shaft340 from the engagement of worm gear 342 with worm 326. When drive shaft340 bidirectionally rotates then, drive shaft 340 will rotate about adrive shaft axis 341. In selected embodiments, the arrangement of worm326 and worm 342 may take advantage of ratios of revolutionstherebetween, in which the ratio of revolutions of the worm to the wormgear may be of the magnitude of about 1:36. Those having ordinary skillin the art, though, will appreciate that the invention is not solimited, and any arrangement and ratio between the worm and the wormgear may be used.

Drive shaft 340, powered by the motor using, for example, worm 326 andworm gear 342, may then be used to provide translational motion forhousing 301, in addition to providing rotation for hub 310. As such, toprovide translational motion for housing 301, pinion gears 346 may beattached to the ends of drive shaft 340. Pinion gears 346 may beconfigured to engage a rack 348, as shown formed along the bottom oftracks 322. Specifically, for example, teeth of pinion gears 346 may beconfigured to engage teeth of rack 348 to transfer the rotation fromdrive shaft 340 and pinion gears 346 into translational motion forhousing 301 of sootblower 300. Thus, by switching rotational directionsof the motor, the translational direction of housing 301 may becontrolled through drive shaft 340 with pinion gears 346 and rack 348.

Further, to provide rotation for hub 310, a rotation delay mechanism 350is attached to drive shaft 340. Rotation delay mechanism 350 isconfigured to transmit rotation from drive shaft 340 to a gear train360. As such, when rotation delay mechanism 350 is engaged andtransmitting rotation from drive shaft 340 to gear train 360, rotationdelay mechanism 350 will delay the transition between rotationaldirections from drive shaft 340 to gear train 360.

Referring still to FIG. 4, rotation delay mechanism 350 may include astatic member 352 and a spur gear 354. Static member 352 is attached todrive shaft 340, and spur gear 354 is disposed about drive shaft 340.Additionally, spur gear 354 is configured to rotate, at least partially,about drive shaft 340. As shown, static member 352 includes pins 356attached thereto and spur gear 354 includes slots 358 formed therein.Pins 356 are then configured to be disposed within slots 358, therebyenabling pins 356 to slidably engage slots 358. As used herein,“slidably engage” refers to the ability of a pin to be disposed within aslot, in which the pin may slide within the slot from one end of theslot to the other end of the slot.

For example, referring briefly to FIG. 5, spur gear 354 having slots 358formed therein in accordance with embodiments disclosed herein is shown.Pins 356 are disposed within slots 358, in which pins 356 are configuredto slidably engage slots 358. Specifically, when slidably engaging slots358, pins 356 are configured to slide within slots 358 from one end ofslots 358 to the other end. As such, pins 356 are then configured toslide within slots 358 such that pins 356 may rotate with respect todrive shaft axis 341. Specifically, in this embodiment, pins 356 mayrotate by about 60 degrees with respect to drive shaft axis 341. Thosehaving ordinary skill in the art will appreciate that the invention isnot so limited though, in which the slots may be of any size and shapeto slidably engage with the pins such that the pins may rotate up toabout 180 degrees with respect to the drive shaft axis.

Referring again to FIG. 4, rotation delay mechanism 350 uses slidableengagement of pins 356 disposed within slots 358 to delay the transitionbetween rotational directions from drive shaft 340 to gear train 360.For example, when drive shaft 340 transitions from rotating clockwise tothe counter-clockwise, the transition of rotation of drive shaft 340also changes the rotation of static member 352 having pins 356 attachedthereto. However, because pins 356 slidably engage slots 358 of spurgear 354, static member 352 will not engage spur gear 354 to rotateuntil pins 356 contact the ends of slots 358. Upon the contact of pins356 with the ends of slots 358, the rotation of static member 352 withrespect to spur gear 354 will be prevented, at which point drive shaft340 may then engage and rotate spur gear 354, and spur gear 354 may thenengage and rotate gear train 360.

As shown, gear train 360 is configured to rotate hub 310, correspondingto the direction of rotation of drive shaft 340. In this embodiment,gear train 360 includes a spur gear 362 with a bevel gear 364 attachedthereto. Spur gear 354 of rotation delay mechanism 350 is configured toengage spur gear 362 of gear train 360 through, for example, theengagement of teeth (not shown) formed thereon. As spur gear 354 rotate,this rotational motion is translated through spur gear 362 to rotatebevel gear 364. Bevel gear 364 is then configured to engage and rotatehub 310. Specifically, bevel gear 364 may engage a bevel gear 311attached to and/or formed upon hub 310. As such, through engagement ofteeth (not shown), for example, bevel gear 364 may rotate bevel gear 311of hub 310.

Referring to FIG. 6, a helical path 680 of a sootblower in accordancewith embodiments disclosed herein is shown. In this embodiment, thesootblower includes a rotation delay mechanism (e.g., 350 in FIG. 4) todelay the transition between rotational directions from the drive shaftto the hub. As shown, when first extended into the boiler, a nozzle of alance attached to the hub may follow an extension path 682. Upon fullextension into the boiler, the motor of the sootblower may then switchdirections to retract the lance from the boiler.

However, because of the inclusion of the rotation delay mechanism withinthe sootblower, the hub and lance may have a delay in transitioningrotational directions from the drive shaft to the hub. Thus, whenretracted from the boiler, the nozzle may follow a retraction path 684,distinct and offset from extension path 682. For example, by includingrotation delay mechanism 350 in sootblower 300, which includes slots 358allowing pins 356 to rotate by about 60 degrees with respect to driveshaft axis 341, extension and retraction paths 682 and 684 may be offsetby about 60 degrees from one another. As such, when the extension andretraction paths are distinct and offset, the path of the nozzle may beimproved to cover more area than that of the standard helical path(shown in FIG. 2) when cleaning.

Those having ordinary skill in the art will appreciate that the presentdisclosure is not limited to a specific arrangement for the rotationdelay mechanism. For example, other arrangements of the pins and slotsmay be used instead. In one embodiment, rather than having the pinsattached to the static member and the slots formed in the spur gear inFIG. 4, the pins may be attached to the spur gear and the slots mayinstead be formed in the static member. Further, in another embodiment,the static member may be eliminated altogether, in which, in FIG. 4, thepins may be attached to the worm gear to slidably engage the spur gear.Furthermore, rather than being limited to the use of pins and slotswithin the rotation delay mechanism, other similar engagements known inthe art may also be used. Thus, those having ordinary skill in the artwill appreciate that other embodiments and arrangements of the rotationdelay mechanism may be formed which do not escape the scope of thepresent disclosure.

Further, the hub, the drive shaft, and the drive assembly may bedisposed within the housing of the sootblower and submerged in alubricant. For example, a lubricant of synthetic oil, or any otherlubricant known in the art, may be disposed and sealed within thehousing of the sootblower. This may be used to preserve and maintain themoving parts disposed within the housing of the sootblower. In such anembodiment, the rollers rotatably attached to the housing and bearingsdisposed therein may be in fluid communication with the housing. Forexample, referring back to FIG. 4, bearings 328, used to facilitaterotation of roller 320, are disposed within roller 320. Sootblower 300may then include a passage 329 extending between roller 320 and housing301. Specifically, passage 329 may be formed inside leg 324, in whichlubricant may flow between bearings 328 of roller 320 and housing 301.Thus, rather than having to continuously replace the lubricant of thebearings within the rollers, these bearings may instead draw from thelubricant disposed inside the housing.

Furthermore, as also shown in FIG. 4, hub 310 may be positionedsubstantially on a vertical centerline 331 of housing 301. In such anembodiment, this enables the majority of the weight of the sootblower(distributed at the hub from the lance and feed tube attached thereto)to be evenly distributed along the drive shaft and amongst the rollersof the sootblower to have a balanced design.

Embodiments of the present disclosure may provide for one or more of thefollowing advantages. First, embodiments disclosed herein may provide amore efficient cleaning of boilers because of the different and varyingpaths used by the nozzles. Specifically, the nozzle may have anincreased amount of paths to follow when cleaning boilers, therebyimproving coverage when cleaning. Next, embodiments disclosed herein mayprovide a more economical sootblower for cleaning of boilers. Forexample, as shown, the sootblower described herein may only include onemotor, thereby preventing cost of an additional motor. Further,embodiments disclosed herein may provide for a sootblower with anincreased working life. For example, because the sootblower describedherein may incorporate a balanced design, in addition to lubricantdisposed therein, the working life of the sootblower may be extended bypreventing unnecessary wear of parts.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims.

1. A sootblower to project a blowing medium into a boiler, thesootblower comprising: a hub, wherein a first end of the hub isconfigured to receive a lance and a second end of the hub is configuredto receive the blowing medium; and a drive assembly configured toconvert bidirectional rotation from a drive shaft to bidirectionalrotation for the hub; wherein drive assembly comprises a rotation delaymechanism configured to delay a transition between a first directionalrotation and a second directional rotation of the bidirectional rotationfor the hub with respect to the drive shaft when the drive shaft istransitioning from a first directional rotation to a second directionalrotation of the bidirectional rotation for the hub.
 2. The sootblower ofclaim 1, wherein the drive assembly comprises a rotation delay mechanismcomprising a first member with a slot formed therein and a second memberhaving a pin attached thereto, wherein the pin of the second member isconfigured to be disposed within the slot of the first member.
 3. Thesootblower of claim 2, wherein one of the first member and the secondmember comprises a static member attached to the drive shaft, whereinthe other of the first member and the second member comprises a spurgear disposed about and configured to rotate about the drive shaft. 4.The sootblower of claim 1, wherein the hub connects the lance to a feedline supplying the blowing medium to the sootblower.
 5. The sootblowerof claim 1, further comprising a housing to contain the drive shaft, thehub, and the rotation delay mechanism.
 6. The sootblower of claim 5,further comprising a lubricant disposed within the housing.
 7. Thesootblower of claim 5, wherein the hub is positioned substantially on avertical centerline of the housing.
 8. The sootblower of claim 1,further comprising pinion gears attached to the drive shaft, wherein thepinion gears are configured to engage a rack to provide translationalmotion for the sootblower.
 9. The sootblower of claim 1, wherein theblowing medium is steam.
 10. The sootblower of claim 1, wherein thelance comprises a venturi nozzle to emit the blowing medium.
 11. Thesootblower of claim 1, further comprising a worm gear attached to thedrive shaft, wherein a motor is configured to provide bidirectionalrotational motion to a worm engaging the worm gear, thereby providingbidirectional rotational motion for the drive shaft.
 12. A driveassembly for a sootblower to project a blowing medium into a boiler, thedrive assembly comprising: a drive shaft; a static member attached tothe drive shaft; and a spur gear disposed about and configured to rotateabout the drive shaft; wherein one of the static member and the spurgear comprises a pin attached thereto; wherein the other of the staticmember and the spur gear comprises a slot formed therein; and whereinthe pin slidably engages the slot.
 13. The drive assembly of claim 12,wherein when the pin slidably engages the slot, the pin is configured torotate by about 60 degrees within the slot with respect to an axis ofthe drive shaft.
 14. The sootblower of claim 12, wherein the driveshaft, the static member, and the spur gear are disposed within ahousing.
 15. The sootblower of claim 14, further comprising a lubricantdisposed within the housing.
 16. The sootblower of claim 15, furthercomprising rollers rotatably attached to the housing with bearingsdisposed therein, wherein the bearings of the rollers are in fluidcommunication with the housing such that the lubricant disposed withinthe housing flows into the rollers to lubricate the bearings.
 17. Thesootblower of claim 16, wherein the lubricant comprises synthetic oil.18. A sootblower used to project a blowing medium, the sootblowercomprising: a housing having a lubricant disposed therein; rollersrotatably attached to the housing and configured to travel along tracks;and bearings disposed inside of the rollers; wherein the bearings of therollers are in fluid communication with the housing.
 19. The sootblowerof claim 18, wherein the lubricant comprises synthetic oil.
 20. Thesootblower of claim 18, further comprising: a hub disposed within thehousing, wherein a first end of the hub is configured to receive a lanceand a second end of the hub is configured to receive the blowing medium;and a drive assembly disposed within the housing, wherein the driveassembly is configured to convert bidirectional rotation from a driveshaft to bidirectional rotation for the hub.